Transcranial Direct Current Stimulation improves working memory and symptoms of Autism and ADHD, say scientists.

Transcranial Direct Current Stimulation (tDCS) method has been found to improve cognitive skills like working memory, sensory processing and behavioural traits related to autism and ADHD ( Attention deficit-Hyperactivity disorder).

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In a recent study 12 young adults suffering from autism, who presented speech impediment and intellectual disability, were subjected to 10 daily applications 20 min/1.5 mA/cathodal (inhibitory) tDCS over the left dorso-lateral pre-frontal cortex, which is responsible for working memory maintenance, attention, set-shifting (update a behavior when the rules change on you), reward evaluation and motor planning.

The results were interesting with 8 out of 10 who completed the full study, showing an improvement in their abnormal behaviours and the significant changes in the subscale assessing hyperactivity and non-compliance.

Adolescents with Autism are more prone to have problems within the working memory system, as neuroimaging studies indicate a more global working memory processing or connectivity deficiency.

But Transcranial Direct Current Stimulation can help in that area too, according to new research on the effects of tDCS on working memory. In a clinical trial published at the journal of cognitive Neuroscience, Sixty-two participants were randomized to receive either right prefrontal, left prefrontal, or sham stimulation with concurrent visuospatial WM training over the course of seven training sessions.

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Results showed that tDCS enhanced training performance, which was preserved several months after training completion. It was also observed stronger effects when tDCS was spaced over a weekend break relative to consecutive daily training, and it was also demonstrated selective transfer in the right prefrontal group to nontrained tasks of visual and spatial WM. These findings shed light on how tDCS may be leveraged as a tool to enhance performance on WM-intensive learning tasks.

Another research studied the effects of 1 mA of current intensity over the left dorsolateral prefrontal cortex for 20 min, in ADHD patients. They found that tDCS increased functional brain connectivity in individuals with ADHD. Furthermore, other clinical trials that used , sham-controlled, crossover design with either 1 mA anodal tDCS over the left dorsolateral prefrontal cortex or with the sham protocol 5 days each with a 2 weeks pause between these conditions, found that the analised ADHD subjects exhibited a significant reduction in inattention and hyperactivity in a standardized working memory test. The described effects were more pronounced 7 days after the end of stimulation, a fact which emphasizes the long-lasting clinical and neuropsychological changes after tDCS.

How does Transcranial Direct Current Stimulation work on the brain?

Some Autistic patients were observed in a recent study to have abnormalities in neocortical circuitry as evidenced by decreased activation in prefrontal and posterior cingulate circuitry during a spatial working memory task. This observation was further proven by analysing the frontal cortex of autistic patients aged 2-9 yrs. In this research it was found that dorsolateral and medial frontal regions were significantly enlarged in autistic patients aged 2 to 5 years compared with control subjects of the same age.

In ADHD patients the lateral prefrontal cortex (middle and inferior frontal gyrus) has been linked to ADHD symptomatology and the kinds of executive functioning with which individuals with ADHD experience difficulties

So, as Transcranial Direct Current stimulation works on the Dorsolateral prefrontal cortex which has been found to be involved with decision making. The symptomatology that affects negatively the quality of life of ADHD and Autistic patients is minimized!